We propose to use the bat wing microcirculatory system for a comprehensive analysis which will draw together physiologic and structural observations. It will be our objective to observe normal and manipulated in vivo responses of the microcirculatory system, to record these responses by microcinematography and photomicrography, and then to process the same field for analysis by light and electron microscopy. Specific problems to be investigated within this methodologic framework will be ultrastructural analysis of the architecture of the microcirculation with respect to identification and classification of microvessels, and with respect to the sphincter-containing regions as identified by in vivo response to stimulation by locally applied vasoactive agents and altered levels of inspired O2 and CO2, and as indicated by the rather extensive bat wing literature. Neural control of the microcirculation will be analyzed by electron microscopic localization of neural profiles and their identification by use by fluorescence and electron microscopic histochemistry for adrenergic and cholinergic terminals, as well as 6-hydroxy-dopamine- induced degeneration of noradrenergic terminals. Regions with previously recorded in vivo activity in vessel walls will be analyzed electron microscopically for intercellular contacts among cellular elements to help establish anatomic evidence for spontaneous electrotonic conduction in vascular smooth muscle.